---
Changes in v2:
 - Remove unnecessary PageSwapCache check from mem_cgroup_swap_full.
 - Do not check swap limit on the legacy hierarchy.

 include/linux/swap.h |  6 ++++++
 mm/memcontrol.c      | 22 ++++++++++++++++++++++
 mm/memory.c          |  3 ++-
 mm/swapfile.c        |  2 +-
 mm/vmscan.c          |  2 +-
 5 files changed, 32 insertions(+), 3 deletions(-)

diff --git a/include/linux/swap.h b/include/linux/swap.h
index c544998dfbe7..5ebdbabc62f0 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h

@@ -552,6 +552,7 @@ extern void mem_cgroup_swapout(struct page *page, swp_entry_t entry);
 extern int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry);
 extern void mem_cgroup_uncharge_swap(swp_entry_t entry);
 extern long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg);
+extern bool mem_cgroup_swap_full(struct page *page);
 #else
 static inline void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
 {

@@ -571,6 +572,11 @@ static inline long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg)
 {
 	return get_nr_swap_pages();
 }
+
+static inline bool mem_cgroup_swap_full(struct page *page)
+{
+	return vm_swap_full();
+}
 #endif
 
 #endif /* __KERNEL__*/

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index e0e498f5ca32..fc25dc211eaf 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c

@@ -5749,6 +5749,28 @@ long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg)
 	return nr_swap_pages;
 }
 
+bool mem_cgroup_swap_full(struct page *page)
+{
+	struct mem_cgroup *memcg;
+
+	VM_BUG_ON_PAGE(!PageLocked(page), page);
+
+	if (vm_swap_full())
+		return true;
+	if (!do_swap_account || !cgroup_subsys_on_dfl(memory_cgrp_subsys))
+		return false;
+
+	memcg = page->mem_cgroup;
+	if (!memcg)
+		return false;
+
+	for (; memcg != root_mem_cgroup; memcg = parent_mem_cgroup(memcg))
+		if (page_counter_read(&memcg->swap) * 2 >= memcg->swap.limit)
+			return true;
+
+	return false;
+}
+
 /* for remember boot option*/
 #ifdef CONFIG_MEMCG_SWAP_ENABLED
 static int really_do_swap_account __initdata = 1;

diff --git a/mm/memory.c b/mm/memory.c
index 3b115dcaa26e..2bd6a78c142b 100644
--- a/mm/memory.c
+++ b/mm/memory.c

@@ -2563,7 +2563,8 @@ int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
 	}
 
 	swap_free(entry);
-	if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
+	if (mem_cgroup_swap_full(page) ||
+	    (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
 		try_to_free_swap(page);
 	unlock_page(page);
 	if (page != swapcache) {

diff --git a/mm/swapfile.c b/mm/swapfile.c
index efa279221302..ab1a8a619676 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c

@@ -1009,7 +1009,7 @@ int free_swap_and_cache(swp_entry_t entry)
 		 * Also recheck PageSwapCache now page is locked (above).
 		 */
 		if (PageSwapCache(page) && !PageWriteback(page) &&
-				(!page_mapped(page) || vm_swap_full())) {
+		    (!page_mapped(page) || mem_cgroup_swap_full(page))) {
 			delete_from_swap_cache(page);
 			SetPageDirty(page);
 		}

diff --git a/mm/vmscan.c b/mm/vmscan.c
index ab52d865d922..1cd88e9b0383 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c

@@ -1206,7 +1206,7 @@ cull_mlocked:
 
 activate_locked:
 		/* Not a candidate for swapping, so reclaim swap space. */
-		if (PageSwapCache(page) && vm_swap_full())
+		if (PageSwapCache(page) && mem_cgroup_swap_full(page))
 			try_to_free_swap(page);
 		VM_BUG_ON_PAGE(PageActive(page), page);
 		SetPageActive(page);

-- 
2.1.4